Earnings (Loss) Per Common Share - Schedule of Computations for Basic and Diluted Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	$ 703	$ 973	$ 1,700	$ 1,780
Net income attributable to noncontrolling interests	(39)	(41)	(78)	(82)
Income from continuing operations attributable to McKesson Corporation	664	932	1,622	1,698
Loss from discontinued operations, net of tax	0	(6)	0	(4)
Net income attributable to McKesson Corporation	$ 664	$ 926	$ 1,622	$ 1,694
Weighted-average common shares outstanding:
Basic (in shares)	134.1	143.1	134.8	143.7
Diluted (in shares)	134.8	144.1	135.7	145.0
Diluted
Continuing operations (in usd per share)	$ 4.92	$ 6.46	$ 11.95	$ 11.71
Discontinued operations (in usd per share)	0	(0.04)	0	(0.03)
Total (in dollars per share)	4.92	6.42	11.95	11.68
Basic
Continuing operations (in usd per share)	4.95	6.51	12.03	11.81
Discontinued operations (in usd per share)	0	(0.04)	0	(0.02)
Total (in dollars per share)	$ 4.95	$ 6.47	$ 12.03	$ 11.79
Stock options
Weighted-average common shares outstanding:
Effect of dilutive securities (in shares)	0.2	0.2	0.2	0.3
Restricted stock units
Weighted-average common shares outstanding:
Effect of dilutive securities (in shares)	0.5	0.8	0.7	1.0